DKIM (DomainKeys Identified Mail) is an email authentication method that adds a digital signature to every message your domain sends. Receiving mail servers use that signature to confirm the message really came from your domain and was not altered along the way. Together with SPF and DMARC, DKIM is one of the pillars of good email deliverability and a strong defence against spoofing.
How DKIM works, in plain terms #
DKIM relies on a pair of cryptographic keys. A private key stays on your mail server and signs your outgoing messages, while a matching public key is published in your domain’s DNS as a TXT record. When your email arrives, the receiving server looks up the public key, checks the signature, and confirms the message is authentic and unchanged. If the check passes, your email is far more likely to be trusted.
Why you should enable DKIM #
- Better inbox placement: signed mail is less likely to be treated as spam.
- Protection against tampering: the signature proves the message was not modified.
- Reputation: it strengthens your domain’s sending reputation over time.
- Required for DMARC: DKIM (or SPF) alignment is needed for DMARC to work fully.
How to set up DKIM #
The good news is that most modern hosting control panels can generate the DKIM key for you, so you rarely need to handle the cryptography yourself. The general process is:
- Log in to your control panel and open the E-mail ou Authentication section.
- Enable DKIM for your domain. The panel generates the key pair automatically.
- If your DNS is managed by the same provider, the TXT record is usually added for you.
- If your DNS is elsewhere, copy the DKIM TXT record shown and add it in your DNS manager.
- Salve e aguarde o tempo necessário para a propagação.
Verifying DKIM is working #
After propagation, send a test email to an address you control and check the message headers, or use a free online DKIM checker. A passing result confirms your signature is valid. If you use an external email service, follow their specific DKIM instructions, since the record name and value are unique to each provider.
Solução de problemas #
- DKIM check fails: confirm the TXT record was copied exactly, with no missing characters.
- No signature on outgoing mail: make sure DKIM is enabled on the sending server.
- Using multiple senders: each service needs its own DKIM record with its own selector.
Precisa de ajuda? #
If DKIM is not validating, our support team can help you check the key and DNS record over live chat.
